Unified some MULLE_BOOTSTRAP_ flags. Split mulle-brew off mulle-bootstrap properly, moved lots of code to a common local environment. Fixed tests. Added two tests.

Just various little things and checks that make life easier, especially if something goes wrong. Minions must be direct subdirectories of parent, and there can be no parent hierarchy. This is implicit ATM. Correct and simplify construction of CFLAGS, LDFLAGS and friends.

Fix script calling. Make things go faster by being less flexible. Improve flags and show output.

Actually add show command to git (sigh). Fix script invocations. There are no pre-fetch and post-fetch scripts anymore. Pre-fetch was never useful. post-fetch can be dealt with in pre-build.sh. Fix script inheritance.